Apparatus and method for supplying liquid and apparatus for processing substrate

ABSTRACT

A liquid supply apparatus comprises a pump mechanism for pumping out a liquid to a conduit, a flowmeter for measuring a flowrate of the liquid flowing through the conduit, and a controller for controlling these mechanisms. The pump mechanism comprises a flexible chamber made of resin, a pressure chamber housing the flexible chamber, and an electro-pneumatic regulator for adjusting pressure in a space between the pressure chamber and the flexible chamber. The flexible chamber comprises a bellows. In the liquid supply apparatus, while pressure is applied to the flexible chamber of the pump mechanism and the liquid in the flexible chamber is pumped out to the conduit, the pressure applied to the flexible chamber is controlled by the controller on the basis of a flowrate of the liquid measured by the flowmeter. This makes it possible to supply the liquid of a small flowrate while controlling the flowrate accurately.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an apparatus and a method for supplyinga liquid and preferably, an apparatus for supplying a liquid is used foran apparatus for processing a substrate.

2. Description of the Background Art

Conventionally, in cleaning a semiconductor substrate (hereinafter,referred to as simply “substrate”), well known a technique where adilute hydrochloric acid (HCl) is used instead of a pure water as acleaning liquid, whereby preventing fine particles in the cleaningliquid from adhering to a surface of the substrate by a Coulomb force.Also, etching of a substrate is performed by using a dilute hydrofluoricacid (HF) or final cleaning of the substrate is performed by using adilute acid solution (hydrochloric acid, hydrofluoric acid or the like).

A cleaning apparatus of a substrate uses a solution which is obtained bydiluting a stock solution of the hydrochloric acid at less than or equalto 1/1000. For simplification or miniaturization or the like of aconstruction of an apparatus, diluted solution is normally produced by amethod (i.e., the so-called direct mixing method) in which a smallamount of an undiluted solution of hydrochloric acid is directlyinjected into a tube for pure water of the cleaning apparatus. In thecleaning apparatus, a flowrate of the hydrochloric acid injected intothe pure water is measured by a flowmeter and by controlling theflowrate of the hydrochloric acid on the basis of an output from theflowmeter, the diluted solution is set at the desired concentration.

In the above case, U.S. Pat. No. 5,672,832 (Document 1) and U.S. Pat.No. 6,578,435 (Document 2) disclose a differential pressure flowmeterfor measuring a flowrate by measuring a pressure difference in the frontand back of a nozzle disposed within a conduit. Japanese PatentApplication Laid Open Gazette No. 2004-226142 (Document 3) and JapanesePatent Application Laid Open Gazette No. 2004-226144 (Document 4)disclose a differential pressure flowmeter where by measuring a pressuredifference in both ends of a capillary, measurement of a very smallflowrate is performed stably.

Japanese Patent Application Laid Open Gazette No. 11-94608 (Document 5)discloses a technique for improving the measuring accuracy of a flowratein a flowmeter including a float which moves up and down according to aflowrate of a fluid in a pipe thereof. Rod-shaped elements projectupward and downward from the float, and a magnet is placed in the pipesurrounding the float and the rod-shaped elements, whereby the float iskept on a center axis of the pipe, and slight vibration is prevented.The document 5 also discloses a technique for adjusting a supply rate ofchemicals in a substrate processing apparatus comprising this flowmeter,where a pneumatic valve positioned in a supply pipe of chemicals iscontrolled on the basis of an output from the flowmeter.

In producing the diluted solution, an extremely small amount ofundiluted solution needs to be injected into the pure water with highaccuracy. For example, in a batch-type cleaning apparatus, a flowrate ofthe undiluted solution is normally less than or equal to 100 ml/min,this very small flowrate needs to be measured high accurately andcontrolled. In a single wafer-type cleaning apparatus, a flowrate of astock (or undiluted) solution is set to be less than or equal to 10ml/min.

Since the differential pressure flowmeters of Documents 1 and 2 maketurbulent flow in the vicinity of the nozzle to measure a flowrate, theyare not suitable for measurement of a very small flowrate having a highpossibility of a laminar flow. In some liquid mass flowmeters formeasuring a very small flowrate, the inside of the flowmeter is coveredwith resin for increasing durability against chemicals, however, it isneeded for the inside of the flowmeter to be covered with thick resinfor durability against a hydrofluoric acid or the like, and it isdifficult to measure a flowrate accurately by these flowmeters.

In the differential pressure flowmeters of Documents 3 and 4, a longcapillary is used as a pressure loss part and assuming that a flow of aliquid in the capillary is laminar, a flowrate is obtained on the basisof an equation with respect to pressure loss in the laminar flow in around tube. However, in the case where the flow is transitional orturbulent, the measuring accuracy of a flowrate decreases, and thus itis important to make a stable laminar flow. Also, since the flowrate isobtained by using the above equation concerning a straight round tube inspite of using the capillary having a bending part actually, itincreases errors of measured flowrate.

In the substrate processing apparatus of Document 5, by controlling thepneumatic valve disposed within the supply pipe of the chemicals, avalve opening (i.e., a degree of a restriction of the supply pipe)changes to adjust the flowrate of the chemicals. It is thereforepossible to supply the chemicals with sufficient accuracy in supply of alarge flowrate, but there is a limit for improving the accuracy of asupply amount in supply of a small flowrate. In a conduit through whichhigh-concentration hydrofluoric acid or hydrochloric acid flows,normally, a region of a valve exposed to a liquid for adjusting aflowrate such as a pneumatic valve or the like is made of fluorocarbonresin. The fluorocarbon resin has a low machining accuracy in comparisonwith metal or the like and it tends to change by an external force orsurrounding temperature. Since a valve for adjusting a flowrate isneeded to adjust a very small cross section of a very small conduitaccurately, it is difficult to form this valve by such material with lowshape stability.

On the other hand, when a liquid of a small flowrate is pumped out, forexample, by an air cylinder without the valve such as the pneumaticvalve or the like for adjusting a flowrate, the piston of the aircylinder needs to move at a very low speed. In this case, since africtional resistance between the cylinder and the piston changesrepeatedly between a static friction and a sliding friction, the pistonvibrates or the air cylinder moves at a higher speed than apredetermined speed repeatedly after the piston is stopped. Thisphenomenon is called chattering or jerking and makes the accuracy of thesupply amount low. In a case where the air cylinder is driven whilepreventing chattering or the like, it is difficult to keep the movingspeed of the piston 1 mm/sec or less.

SUMMARY OF THE INVENTION

The present invention is intended for a liquid supply apparatus forsupplying a liquid. The liquid supply apparatus comprises a pumpmechanism for pumping out a liquid to a conduit by applying pressure toa flexible chamber to reduce a volume of the flexible chamber, aflowmeter placed in a downstream side of the pump mechanism formeasuring a flowrate of the liquid flowing through the conduit, and acontroller for sending an electrical signal to the pump mechanism, theelectrical signal controlling pressure applied to the flexible chamberso that the flowrate of the liquid flowing through the conduit isadjusted to a predetermined flowrate on the basis of a flowrate of theliquid obtained by the flowmeter. According to the liquid supplyapparatus in accordance with the present invention, it is possible tosupply the liquid of a small flowrate while controlling the flowrateaccurately.

According to one preferred embodiment of the present invention, sincethe flexible chamber is made of resin, it is possible to supply variouskinds of liquid. According to another preferred embodiment of thepresent invention, since the flexible chamber comprises a bellows, it ispossible to change a volume of the flexible chamber easily and suppressdeterioration of the flexible chamber.

According to still another preferred embodiment of the presentinvention, the pump mechanism comprises a pressure chamber housing theflexible chamber, and an electro-pneumatic regulator for adjustingpressure in a space between the pressure chamber and the flexiblechamber. This makes it possible to control the pressure in the spacebetween the pressure chamber and the flexible chamber with high responseand high accuracy.

According to an aspect of the present invention, the liquid supplyapparatus further comprises the other pump mechanism which has the sameconstituents as the pump mechanism, and in the apparatus, compression ofone chamber of the flexible chamber of the pump mechanism and the otherflexible chamber of the other pump mechanism and concurrent expansion ofthe other chamber of the flexible chamber and the other flexible chamberare performed alternately to the flexible chamber and the other flexiblechamber by control of the controller. This makes it possible to supplythe liquid of a small flowrate long hours continuously while controllingthe flowrate accurately.

According to another aspect of the present invention, the flowmeter is adifferential pressure flowmeter, and the differential pressure flowmetercomprises a round tube provided as a part of the conduit in which a flowof the liquid with a Reynolds number less than or equal to 2000 isformed, a first pressure sensor placed between the pump mechanism andthe round tube for measuring a pressure of the liquid flowing into theround tube, and a second pressure sensor placed in a downstream side ofthe round tube for measuring a pressure of the liquid flowing out of theround tube. This makes it possible to measure the flowrate with highaccuracy stably.

The present invention is also intended for a method for supplying aliquid and also intended for a substrate processing apparatus comprisingthe liquid supply apparatus.

These and other objects, features, aspects and advantages of the presentinvention will become more apparent from the following detaileddescription of the present invention when taken in conjunction with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view illustrating a construction of a liquid supplyapparatus in accordance with a first preferred embodiment;

FIG. 2 and FIG. 3 are enlarged views illustrating the vicinity of aflexible chamber and a pressure chamber;

FIG. 4 and FIG. 5 are a front view and a plan view illustrating aconstruction of a flowmeter;

FIG. 6 is a graph illustrating a relation between a pressure differenceand a flowrate;

FIG. 7 is a view illustrating an operation flow of the liquid supplyapparatus for supplying a liquid;

FIG. 8 is a view illustrating an operation flow of the liquid supplyapparatus for controlling a flowrate;

FIG. 9 is a view illustrating a pump mechanism of a comparative example;

FIG. 10 is a view illustrating a construction of a liquid supplyapparatus in accordance with a second preferred embodiment;

FIG. 11 and FIG. 12 are views illustrating an operation flow of theliquid supply apparatus for supplying a liquid;

FIG. 13 is a view illustrating a state of switching between a first pumpmechanism and a second pump mechanism;

FIG. 14 is a view illustrating an operation flow of the liquid supplyapparatus for controlling a flowrate;

FIG. 15 is a view illustrating a change of a flowrate;

FIG. 16 is a view illustrating a pump mechanism of a liquid supplyapparatus in accordance with a third preferred embodiment; and

FIG. 17 and FIG. 18 are views illustrating substrate processingapparatuses in accordance with fourth and fifth preferred embodiments.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 is a view illustrating a construction of a liquid supplyapparatus 1 in accordance with the first preferred embodiment of thepresent invention. The liquid supply apparatus 1 comprises a conduit 11through which a liquid flows, a liquid supply source 12 connected to anupstream side of the conduit 11 for storing the liquid, a pump mechanism13 placed in a downstream side of the liquid supply source 12 forstoring the liquid supplied from the liquid supply source 12 to pump outthe liquid to a downstream side of the conduit 11, a differentialpressure flowmeter 14 placed in a downstream side of the pump mechanism13 for measuring a flowrate of the liquid flowing through the conduit 11(i.e., an amount of the liquid flowing through the conduit 11 per unittime), and a controller 15 for controlling these mechanisms. On theconduit 11, a first filter 111 and a first check valve 112 are installedbetween the liquid supply source 12 and the pump mechanism 13, a secondcheck valve 113 is installed between the pump mechanism 13 and theflowmeter 14, and a pressure control tube 147 and a second filter 114are installed on a downstream side of the flowmeter 14. In FIG. 1,hatching of cross sections are omitted.

The liquid supply source 12 is a bottle, a region exposed to the liquidof the bottle is covered with fluorocarbon resin (for example, PTFE(poly-tetra-fluoro-ethylene)), and the top of the bottle is open to theatmosphere. Stock solution such as hydrochloric acid, hydrofluoric acid,or the like is stored in the liquid supply source 12 and the stocksolution is supplied to the pump mechanism 13 through the conduit 11.The first filter 111 is made of PTFE, for example and removes impuritiessuch as particles and the like from the liquid which is supplied to thepump mechanism 13. The second filter 114 is also made of thefluorocarbon resin such as PTFE or the like and has a mesh of 0.05 μm,for example. In the liquid supply apparatus 1, the second filter 114removes impurities from the liquid which is supplied from the liquidsupply apparatus 1 to other apparatus and the like.

The whole of the first check valve 112 and the second check valve 113are made of PFA (per-fluoro-alkoxy), for example and the first checkvalve 112 and the second check valve 113 prevent the liquid from flowingback from a downstream side to an upstream side of each check valve.Each of the first check valve 112 and the second check valve 113 mayhave constituents where a sapphire ball and a sapphire valve seat areprovided in its outer casing made of the fluorocarbon resin.

The region exposed to the liquid of the liquid supply source 12, thefirst filter 111, the second filter 114, the first check valve 112, andthe second check valve 113 are made of the fluorocarbon resin or thelike, and thus they have high durability (mainly, corrosion resistance)against various kinds of liquid. The pressure control tube 147 will bediscussed later together with the detailed description of the flowmeter14.

The pump mechanism 13 comprises a flexible chamber 131 which is flexibleand made of resin, an approximately cylindrical shaped pressure chamber132 housing the flexible chamber 131 having an approximately cylindricalshape, and an electro-pneumatic regulator 133 and an ejector 134 forsupplying or discharging air to/from the pressure chamber 132 to adjustpressure in a space between the pressure chamber 132 and the flexiblechamber 131. The flexible chamber 131 is connected to the conduit 11between the first check valve 112 and the second check valve 113. Theelectro-pneumatic regulator 133 and the ejector 134 are respectivelyconnected to the pressure chamber 132 through pneumatic valves 1331,1341.

The flexible chamber 131 comprises a bellows 1311 as a part thereof.Materials, such as PTFE, PFA, PEEK (poly-ether-ether-ketone), PCTFE(poly-chloro-trifluoro-ethylene), ETFE (ethylene-tetrafluoro-ethylene),FEP (fluorinated-ethylene-propylene) or the like, are available for theflexible chamber 131. A material for the flexible chamber 131 isdetermined on the basis of various kinds of liquid to be pumped out. Inthe preferred embodiment, the flexible chamber 131 is made of PFA or thelike such as fluorocarbon resin. Since the pressure chamber 132 is not,normally, exposed to the liquid stored in the flexible chamber 131, thepressure chamber 132 may be made of vinyl chloride or the like which hasslightly lower durability against liquid than the flexible chamber 131.

The electro-pneumatic regulator 133 comprises an air inlet connected toan external compressor for applying pressure, an air outlet forpressure-relief, and an outlet connected into the pressure chamber 132for adjusting the pressure in the space between the pressure chamber 132and the flexible chamber 131. The electro-pneumatic regulator 133controls the pressure in the space between the pressure chamber 132 andthe flexible chamber 131 steplessly and continuously to be a directedpressure on the basis of an electrical signal (i.e., in proportion to aninput current or the like) sent from a feedback controller 151 of thecontroller 15. When the electro-pneumatic regulator 133 controls thepressure in the pressure chamber 132, the pneumatic valve 1331 is openedby an electromagnetic valve 1332 which is driven by a sequencecontroller 152 of the controller 15.

The ejector 134 is connected to the external compressor through aregulator 1343 and a pneumatic valve 1344. When the ejector 134discharges air in the pressure chamber 132, pneumatic valves 1341, 1344are opened by electromagnetic valves 1342, 1345 driven by the sequencecontroller 152, air supplied from the external compressor flows out ofthe ejector 134 at high speed, and then air in the pressure chamber 132is discharged through the ejector 134. In the pump mechanism 13, theelectromagnetic valves may be used instead of the pneumatic valves 1331,1341, 1344.

FIG. 2 and FIG. 3 are enlarged views illustrating the vicinity of theflexible chamber 131 and the pressure chamber 132 of the pump mechanism13. FIG. 2 and FIG. 3 respectively illustrate states where the flexiblechamber 131 is expanded and compressed. In the pump mechanism 13, anupper end 1312 of the flexible chamber 131 having the bellows 1311 isfixed to the pressure chamber 132 and an lower end 1313 is made free.

In the pump mechanism 13, the electro-pneumatic regulator 133 (seeFIG. 1) supplies air from the bottom of the pressure chamber 132 (i.e.,a part opposed to the lower end 1313 of the flexible chamber 131) intothe pressure chamber 132, pressure is applied to the flexible chamber131, and then the flexible chamber 131 in the state shown in FIG. 2(hereinafter, referred to as “expanded state”) is compressed andgradually changes to the state shown in FIG. 3 (hereinafter, referred toas “compressed state”). With this operation, the liquid stored in theflexible chamber 131 is pumped out to the conduit 11 by applyingpressure to the flexible chamber 131 to reduce a (internal) volume ofthe flexible chamber 131. The check valve 112 prevents the liquid pumpedout of the flexible chamber 131 from flowing into the liquid supplysource 12 (i.e., the upstream side) and the liquid flows to theflowmeter 14 (i.e., the downstream side) through the check valve 113.

In the pump mechanism 13, the ejector 134 (see FIG. 1) discharges airfrom the bottom of the pressure chamber 132, the pressure in thepressure chamber 132 changes to be negative, and then the flexiblechamber 131 changes gradually from the compressed state shown in FIG. 3to the expanded state shown in FIG. 2. With this operation, by expandingthe flexible chamber 131 to increase a volume of the flexible chamber131, the liquid is sucked from the liquid supply source 12 through theconduit 11 and the check valve 112, the sucked liquid flows into theflexible chamber 131, and it is stored in the flexible chamber 131. Atthis time, the check valve 113 prevents suction of the liquid from thedownstream side of the pump mechanism 13.

In the pump mechanism 13, a volume of a space between the flexiblechamber 131 and the pressure chamber 132, that is to say, a volume of aspace where pressure is controlled by the electro-pneumatic regulator133, is made small, and this improves response of transition betweensuction of the liquid from the liquid supply source 12 to the flexiblechamber 131 and pumping out of the liquid from the flexible chamber 131.

As shown in FIG. 2 and FIG. 3, the pump mechanism 13 further comprises adisplacement sensor 135 for detecting a displacement of the lower end1313 which is a free end of the flexible chamber 131 with respect to thepressure chamber 132, and a leakage sensor 136 for detecting a leakage,if there is a leakage of the liquid from the flexible chamber 131.

The displacement sensor 135 comprises two pairs of light emitting parts1351 and light receiving parts 1352 on a side wall of the pressurechamber 132 (i.e., inner surface parallel to a direction of expansionand compression of the bellows 1311). Each pair of the light emittingparts 1351 and the light receiving parts 1352 is positioned in the bothsides of the flexible chamber 131 in the expanded state shown in FIG. 2.Location of one pair with respect to the direction of expansion andcompression of the flexible chamber 131 is almost same as the locationof the lower end 1313 of the flexible chamber 131 in the expanded state,and location of the other pair is slightly lower than the location ofthe lower end 1313 of the flexible chamber 131 in the compressed stateshown in FIG. 3.

In the pump mechanism 13, when the flexible chamber 131 is in theexpanded state shown in FIG. 2, the flexible chamber 131 blocks lightsfrom the two light emitting parts 1351, the displacement sensor 135determines the flexible chamber 131 is in the expanded state. When theflexible chamber 131 is in the compressed state shown in FIG. 3, lightsfrom the two light emitting parts 1351 pass through the inner space ofthe pressure chamber 132, the light receiving parts 1352 receive thelights, and then the displacement sensor 135 determines the flexiblechamber 131 is in the compressed state. In a case where a light from onelight emitting part 1351 which is located near the bottom of thepressure chamber 132 is received by the opposed light receiving part1352 and a light from the other light emitting part 1351 does not reachthe light receiving part 1352, the displacement sensor 135 determinesthe flexible chamber 131 is in an intermediate state between the stateof FIG. 2 and that of FIG. 3.

The leakage sensor 136 comprises a pair of electrodes 1361, and the pairof electrodes 1361 is positioned in the bottom of grooves 1321 locatedon an inner side of the bottom of the pressure chamber 132. In the pumpmechanism 13, in a case where the liquid leaks from the flexible chamber131, the leaked liquid collects in the grooves 1321 at the bottom of thepressure chamber 132, and the pair of electrodes 1361 is electricallyconnected each other through the liquid (electrolyte solution) in thegrooves 1321. The leakage sensor 136 detects conduction between the pairof electrodes 1361 to detect the leakage of the liquid from the flexiblechamber 131.

FIG. 4 and FIG. 5 are a front view and a plan view illustrating aconstruction of the flowmeter 14, respectively. As shown in FIG. 4 andFIG. 5, the flowmeter 14 comprises a tube 143 provided as a part of theconduit 11 (see FIG. 1) and which is a pressure loss part having acircular section (i.e., round tube), a tube base 144 to which the tube143 is attached, a first pressure sensor 141 placed between the pumpmechanism 13 (see FIG. 1) and the tube 143 (in the left of FIG. 4 andFIG. 5) for measuring a pressure of the liquid flowing into the tube 143and a second pressure sensor 142 placed in a downstream side of the tube143 for measuring a pressure of the liquid flowing out of the tube 143.As shown in FIG. 4, the flowmeter 14 further comprises a storage part145 for storing information and an operation part 146 for performingvarious computations.

The tube 143 is made of resin and has high durability (mainly, corrosionresistance) against various kinds of liquid. The tube 143 hasflexibility and is formed in a coil above the tube base 144 as shown inFIG. 4. Materials, such as PEEK, PTFE, PCTFE, PFA, ETFE, FEP, or thelike, are available for the tube 143. A material for the tube 143 isdetermined on the basis of various kinds of liquid to be measured, aninner diameter of the tube 143, or the like. In the first preferredembodiment, the tube 143 is made of PFA.

The inner diameter of the tube 143 is determined on the basis of themaximum value of a measured flowrate of the flowmeter 14 such that aReynolds number of a flow of the liquid within the tube 143 is made atless than or equal to 2000. The Reynolds number is the dimensionlessnumber indicating the type of a flow (i.e., a flow is laminar orturbulent). When a Reynolds number of a flow is smaller than a criticalReynolds number (about 2000 to 2300), the flow is kept laminar. AReynolds number Re within the tube 143 having a circular section isexpressed as Eq. 1 where D (m) is the inner diameter of the tube 143.Re=ρUD/μ=4 ρQ/πμD   Eq. 1

In Eq. 1, ρ is density (kg/m³) of the liquid flowing through the tube143, μ is coefficient of viscosity (N·s/m²) of the liquid, U is averageflowing velocity (m/s) of the liquid in a cross-sectional area verticalto a longitudinal direction of the tube 143, and Q is a flowrate (m³/s)of the liquid.

In the flowmeter 14, the maximum value of a Reynolds number within ameasuring range (i.e., a Reynolds number at the maximum of the measuredflowrate) is set to be less than or equal to 2000 and laminar flowoccurs within the tube 143. For this reason, an inlet length X(m)necessary for full development of the flow of the liquid (i.e., velocitydistribution of the flow within the cross-sectional area of the tube 143goes into a constant state) is expressed as Eq. 2 for the Boussinesqequation by using the Reynolds number Re and the inner diameter D(m) ofthe tube 143.X≧0.065 Re·D   Eq. 2

The length of the tube 143 is preferably set to be 130 or more timesthan the inner diameter of the tube 143 so that the length of whichbecomes longer than the inlet length even if the Reynolds Number is2000. The length of the tube 143 is determined on the basis of apressure loss required in the tube 143 (i.e., a pressure differencebetween both ends of the tube 143), and an outer diameter of the tube143 is set to be 1.5 or more times larger than the inner diameter so asto ensure mechanical strength of the tube 143 of resin.

The tube base 144 is a block of resin (made of PTFE which is thefluorocarbon resin, for example) and has two L-shaped channels therein.As shown in FIG. 4, both ends of the tube 143 are detachably attached atthe top of the tube base 144 through tube fittings of resin. As the tubefittings, various small diameter fittings for liquid chromatography orthe like can be used. The inside channels of the tube base 144, the tube143, inside channels of the first pressure sensor 141 and the secondpressure sensor 142 (later discussed), and pressure transducers 1411,1421 are also provided as parts of the conduit 11 of the liquid supplyapparatus 1.

As shown in FIG. 4 and FIG. 5, the first pressure sensor 141 and thesecond pressure sensor 142 comprise approximately cylindrical pressuretransducers 1411, 1421, and the pressure transducers 1411, 1421 are easyto exhaust air while injecting the liquid because their heights are low.As shown in FIG. 4, members 1412, 1422 which are positioned in thepressure transducers 1411, 1421 and exposed to the liquid are made ofresin (PTFE which is fluorocarbon resin, for example). In the firstpressure sensor 141 and the second pressure sensor 142, the insidechannels and the pressure transducers 1411, 1421 are connected directlyand therefore this prevents accumulation of the liquid. Both ends of theinside channels of the first pressure sensor 141 and the second pressuresensor 142 have fittings which allow easy connection. In the firstpreferred embodiment, the first pressure sensor 141 and the secondpressure sensor 142 have a measuring range from 0 to 0.2 Mpa(megapascal).

In the flowmeter 14, the liquid flows into the first pressure sensor 141from the upstream side continuously, the liquid passes through the firstpressure sensor 141, the tube base 144, the tube 143, and the secondpressure sensor 142 sequentially, and then flows out to the downstreamside. While the liquid is passing through the flowmeter 14, a flowrateof the liquid is measured continuously. Next discussion will be made onan operation flow of the flowmeter 14 for measuring a flowrate of theliquid.

While the liquid is flowing through the flowmeter 14, a pressure of theliquid flowing into the tube 143 is measured by the first pressuresensor 141 and a pressure of the liquid flowing out of the tube 143 ismeasured by the second pressure sensor 142. Outputs from the firstpressure sensor 141 and the second pressure sensor 142 (for example, theoutputs are values of pressures to be measured which are converted toelectrical signals ranging from 4 to 20 mA (milliampere) by both thepressure sensors) are transmitted to a subtracter 1461 of an operationpart 146, the output of the second pressure sensor 142 is subtractedfrom the output of the first pressure sensor 141 in the subtracter 1461,and then a pressure difference between both ends of the tube 143 isobtained.

FIG. 6 is a graph illustrating a relation (hereinafter referred to as“flowrate information”) between the pressure difference between bothends of the tube 143 and the flowrate of the liquid flowing through thetube 143. As shown in FIG. 6, the pressure difference and the flowratehave an approximately proportionality relation in the flowmeter 14.Since the flow within the tube 143 is laminar where the Reynolds numberis less than or equal to 2000, the pressure difference and the flowrateshould be directly proportioned theoretically. The reason why thepressure difference and the flowrate are not perfectly proportioned isconsidered as an effect of the flow in the vicinity of both ends of thetube 143, a state of an inside surface of the tube 143, and the like.

Before the flowmeter 14 is actually installed in the liquid supplyapparatus 1, the flowrate information is obtained by the followingmethod in advance. A syringe pump is attached to the upstream side ofthe first pressure sensor 141 and the liquid (preferably, the purewater) is injected at a constant ejection rate. The injected liquidpasses through the first pressure sensor 141, the tube base 144, thetube 143, and the second pressure sensor 142, and flows out of theflowmeter 14. In the first pressure sensor 141 and the second pressuresensor 142, pressures in passing of the liquid are measured and apressure difference is obtained. After the passage of a predeterminedtime, a weight of the liquid flowing out of the flowmeter 14 is measuredand a flowrate corresponding to the pressure difference is obtained.Then, by changing the ejection rate of the syringe pump and repeatingmeasurement of the pressure difference and the flowrate, the flowrateinformation shown in FIG. 6 is obtained. This obtained flowrateinformation is stored in the storage part 145 before actual use of theflowmeter 14.

In the flowmeter 14 shown in FIG. 4, the pressure difference betweenboth ends of the tube 143 obtained by the subtracter 1461 is transmittedto a linearizer 1462 as an electrical signal ranging from 0 to 5V, forexample, and the flowrate information stored in the storage part 145 inadvance is read out by the linearizer 1462. In the linearizer 1462, aflowrate of the liquid flowing through the tube 143 is determinedautomatically on the basis of the pressure difference and the flowrateinformation. The flowrate information stored in the storage part 145 maybe a tabular form or an approximation formula, for example.

Referring back to FIG. 1, the discussed pressure control tube 147 isinstalled between the flowmeter 14 and the second filter 114. Thepressure control tube 147 is made of resin with high durability againstvarious kinds of liquid. The pressure control tube 147 also hasflexibility and is formed in a coil.

In the liquid supply apparatus 1, since the liquid passes through thepressure control tube 147 before the liquid flowing out of the flowmeter14 is supplied to another apparatus or the like through the secondfilter 114, pressure of the liquid becomes relatively low. For thisreason, even if a required pressure in supplying the liquid from theliquid supply apparatus 1 is almost equal to an atmospheric pressure, itcan be avoided that a pressure to be measured (i.e., a pressuredifference between a pressure of the liquid and an atmospheric pressure)in the second pressure sensor 142 of the flowmeter 14 nears to 0 wherethe measuring accuracy becomes low. This improves the measuring accuracyof a flowrate by the flowmeter 14. From the viewpoint of improving themeasuring accuracy of the flowrate, it is preferable that the length ofthe pressure control tube 147 is determined so that the minimum value ofa pressure measured by the second pressure sensor 142 falls in a range10% or more (in the preferred embodiment, the range is 20 kPa or more)from the bottom of the measuring range of the second pressure sensor142, for example.

Next discussion will be made on an operation flow of the liquid supplyapparatus 1 for supplying the liquid referring to FIG. 7. When theliquid is supplied by the liquid supply apparatus 1, a user fills thepump mechanism 13 and the conduit 11 with liquid for preparation. In theliquid filling, an end of the downstream side of the conduit 11 isconnected to a drain.

The sequence controller 152 of the controller 15 shown in FIG. 1 closesthe pneumatic valve 1331 of the pump mechanism 13 and opens thepneumatic valves 1341, 1344. The ejector 134 discharges air between theflexible chamber 131 and the pressure chamber 132, and then pressurereduction in the pressure chamber 132 is started. By this, the flexiblechamber 131 which is in the compressed state (see FIG. 3) in advance isexpanded, and the liquid is sucked from the liquid supply source 12 tobe supplied to the flexible chamber 131 and stored therein. Thedisplacement sensor 135 (see FIG. 2) detects that the flexible chamber131 changed to the expanded state (see FIG. 2), and the pneumatic valves1341, 1344 are closed to complete liquid supply to the flexible chamber131 (Step S11). In the preferred embodiment, an amount of the liquidsupplied to the flexible chamber 131 in one expansion is 30 ml and avolume of the flexible chamber 131 in the expanded state is 100 ml.

Subsequently, the user confirms whether or not air remains in theflexible chamber 131 and the conduit 11 (Step S12). In a case where airremains, the sequence controller 152 opens the pneumatic valve 1331, andthe electro-pneumatic regulator 133 starts supplying air between theflexible chamber 131 and the pressure chamber 132 to increase thepressure in the pressure chamber 132 (i.e., pressure around the flexiblechamber 131). The flexible chamber 131 is compressed by the increase ofthe pressure, and air remaining in the flexible chamber 131 and theconduit 11 is discharged from the downstream side of the conduit 11 tothe outside of the liquid supply apparatus 1.

After the displacement sensor 135 detects the flexible chamber 131changed to the compressed state, the pneumatic valve 1331 is closed anddischarge of air in the flexible chamber 131 and the conduit 11 isstopped (Step S121), and liquid supply to the flexible chamber 131 isrestarted back to Step S11. In the liquid supply apparatus 1, liquidsupply to the flexible chamber 131 and discharge of air from theflexible chamber 131 and the conduit 11 (Steps S11 to S121) are repeateduntil air in the flexible chamber 131 and the conduit 11 is completelydischarged and the liquid filling is finished.

After air in the flexible chamber 131 and the conduit 11 is completelydischarged (Step S12), the end of the downstream side of the conduit 11is connected to an external apparatus or the like to be supplied. Likein Step S121, the electro-pneumatic regulator 133 supplies air to thepressure chamber 132 to apply pressure to the flexible chamber 131, andthe flexible chamber 131 in the expanded state is compressed. The liquidstored in the flexible chamber 131 is pumped out to the conduit 11 andsupplied to the external apparatus or the like (Step S13). In the liquidsupply apparatus 1, while the pump mechanism 13 is pumping out theliquid from the flexible chamber 131, a flowrate control shown in FIG. 8is continuously performed. Next discussion will be made on an operationflow of the liquid supply apparatus 1 for controlling a flowrate.

In the liquid supply apparatus 1, when pumping out of the liquid fromthe pump mechanism 13 to the conduit 11 is started, a flowrate of theliquid flowing through the conduit 11 is measured by the flowmeter 14which is placed in the downstream side of the pump mechanism 13, and ameasured flowrate is sent to the feedback controller 151 of thecontroller 15 (Step S131). Subsequently, the feedback controller 151determines whether or not the measured flowrate obtained by theflowmeter 14 is equal to a predetermined flowrate which is inputted fromthe outside (Step S132).

In a case where the measured flowrate differs from the predeterminedflowrate, the feedback controller 151 sends a command value of pressureas an electrical signal to the electro-pneumatic regulator 133 of thepump mechanism 13 on the basis of the measured flowrate and controlspressure applied to the flexible chamber 131 so that the flowrate of theliquid flowing through the conduit 11 is adjusted to the predeterminedflowrate (Step S133). In a case where the measured flowrate is equal tothe predetermined flowrate, the pressure applied to the flexible chamber131 is kept. In the preferred embodiment, the feedback controller 151utilizes a PID Control as a control method of the flowrate. Anelectrical signal sending from the feedback controller 151 to theelectro-pneumatic regulator 133 is a current ranging from 4 to 20 mA.

In the pump mechanism 13, since a reaction force by the bellows 1311 ofthe flexible chamber 131 increases gradually with compression of theflexible chamber 131, normally, control of the electro-pneumaticregulator 133 is performed so that the pressure in the space between theflexible chamber 131 and the pressure chamber 132 increases gradually tomake the measured flowrate equal to the predetermined flowrate.

In the liquid supply apparatus 1, it is checked repeatedly whetherpumping out of the liquid from the pump mechanism 13 is complete or not(Step S134), and while pumping out of the liquid from the flexiblechamber 131 is performed, steps for measuring a flowrate to control thepressure applied to the flexible chamber 131 (Steps S131 to 133) arerepeated. With this operation, in the liquid supply apparatus 1, liquidsupply to the external apparatus or the like is performed whilecontrolling the flowrate so that the flowrate of the liquid flowingthrough the conduit 11 is adjusted to the predetermined flowrate. Afterthe displacement sensor 135 detects the flexible chamber 131 changed tothe compressed state, the pneumatic valve 1331 is closed, and pumpingout of the liquid from the flexible chamber 131 to the conduit 11 isfinished (Step S134). Flowrate measurement by the flowmeter 14 andcontrol of the electro-pneumatic regulator 133 by the controller 15 arealso ended, and then liquid supply to the external apparatus or the likeis complete. In the preferred embodiment, an amount of liquid supply inone compression of the flexible chamber 131 is 30 ml.

In a case where liquid supply of the liquid supply apparatus 1 isrepeated, backing to Step S11 after Step S13, the flexible chamber 131is reexpanded and the liquid is sucked from the liquid supply source 12(not shown in FIG. 7). In this case, when the flexible chamber 131 isexpanded, since in the flexible chamber 131 and the conduit 11 air doesnot remain and the liquid is filled, steps for discharging air from theflexible chamber 131 and the conduit 11 (Steps S12, S121) are omitted,and then Steps S11 and S13 are repeated.

As discussed above, in the liquid supply apparatus 1, while pressure isapplied to the flexible chamber 131 of the pump mechanism 13 and theliquid in the flexible chamber 131 is pumped out to the conduit 11, theflowrate of the liquid flowing through the conduit 11 is measured by theflowmeter 14, and the pressure applied to the flexible chamber 131 iscontrolled by the feedback controller 151 so that the measured flowrateis adjusted to the predetermined flowrate. In the liquid supplyapparatus 1, by controlling the pressure applied to the flexible chamber131 with high accuracy, it is possible to supply the liquid of a smallflowrate while controlling the flowrate accurately.

In the liquid supply apparatus 1, since the flexible chamber 131 of thepump mechanism 13 and the tube 143 of the flowmeter 14 are made of resinwith high durability against various kinds of liquid and the othervarious constituent elements which are exposed to the liquid are made ofmaterials such as fluorocarbon resin or the like with high durability,it is possible to perform supply of various kinds of liquid.

In the pump mechanism 13, since the flexible chamber 131 comprises thebellows 1311, it is possible to change a volume of the flexible chamber131 easily, that is to say, by a small pressure. Since, in compressingthe flexible chamber 131, the whole of the bellows 1311 is compressed,it is prevented that the bending of the flexible chamber 131 incompressing occurs in a part of the flexible chamber 131, and it ispossible to suppress deterioration caused by repeats of compression andexpansion of the flexible chamber 131 in using the pump mechanism 13.

In the pump mechanism 13, since the electro-pneumatic regulator 133adjusts the pressure in the pressure chamber 132 housing the flexiblechamber 131, it is possible to control the pressure in the space betweenthe pressure chamber 132 and the flexible chamber 131 with high responseand high accuracy.

In the pump mechanism 13, the lower end 1313 of the flexible chamber 131is made free as shown in FIG. 2. FIG. 9 is a view illustrating a part ofa pump mechanism 93 where a lower end of a flexible chamber is not madefree as a comparative example. In the pump mechanism 93 of thecomparative example, a cylinder part 9322 is provided at a lower part ofa pressure chamber 932, and inside the cylinder part 9322 a piston 9323passing through the bottom of the flexible chamber 932 to be connectedto a lower end 9313 of a flexible chamber 931 is provided. The piston9323 comprises a disk-shaped bottom part 9324 positioned inside of thecylinder part 9322 and a cylindrical shaft 9325 projecting upward fromthe bottom part 9324 to be inserted into a through-hole 9326 in thebottom of the pressure chamber 932. Sealing is provided between thebottom part 9324 and an internal surface of the cylinder part 9322, andbetween an external surface of the shaft 9325 and an internal surface ofthe through-hole 9326 so that air does not leak.

In the pump mechanism 93, by supplying air between the pressure chamber932 and the flexible chamber 931 to compress the flexible chamber 931,the liquid in the flexible chamber 931 is pumped out. Also, air issupplied to a space surrounded by the bottom of the pressure chamber932, the cylinder part 9322, and the bottom part 9324 of the piston9323, the bottom part 9324 of the piston 9323 gets away from the bottomof the pressure chamber 932 relatively. The flexible chamber 931 isexpanded and the liquid is supplied to the flexible chamber 931.

In the pump mechanism 93, in any case of pumping out the liquid from theflexible chamber 931 and supplying the liquid to the flexible chamber931, the piston 9323 moves up and down together with the lower end 9313of the flexible chamber 931. In movement of the piston 9323, since thebottom part 9324 rubs with the internal surface of the cylinder part9322 and the shaft 9325 rubs with the internal surface of thethrough-hole 9326, frictional resistance occurs. When the piston 9323moves at low speed, chattering or jerking occurs in up and downmovements of the lower end 9313 of the flexible chamber 931, andcompression and expansion of the flexible chamber 931 becomes unstable.

On the other hand, in the pump mechanism 13 in accordance with the abovepreferred embodiment, since the lower end 1313 of the flexible chamber131 is made free as shown in FIG. 2, it is possible to compress theflexible chamber 131 stably (i.e., while preventing occurrence of thechattering or jerking) by preventing rubbing against the pressurechamber 132 of the flexible chamber 131 or by making the frictionalresistance very small even if rubbing occurs. As a result, it ispossible to control the flowrate of the liquid to be supplied withhigher accuracy in the liquid supply apparatus 1.

In the pump mechanism 13, by providing the displacement sensor 135 fordetecting a displacement of the lower end 1313 of the flexible chamber131, it is possible to monitor movement of the flexible chamber 131 inthe pressure chamber 132, and it is therefore possible to increasereliability of the liquid supply apparatus 1. By positioning the leakagesensor 136 at the bottom of the pressure chamber 132, even if the liquidleaks from the flexible chamber 131, the leakage of the liquid isdetected immediately, and it is further possible to increase reliabilityof the liquid supply apparatus 1.

In the flowmeter 14, the flow of the liquid is kept laminar, and thenthe pressure difference between both ends of the tube 143 and theflowrate have the approximately proportionality relation. This preventsresolution of the pressure difference and the flowrate from changingconsiderably and makes the measuring accuracy of the flowrate almostconstant regardless of the pressure difference. Since a change of theflowrate relative to that of the pressure difference increases, incomparison with another measurement within turbulent region where theflowrate is approximately proportioned to square root of the pressuredifference, the measuring accuracy can be improved and further the rangeof the flowrate which can be measured is expanded. In the flowmeter 14,the Reynolds number of the flow within the tube 143 is kept to be lessthan or equal to 2000 and a transitional flow where a state of the flowbecomes unstable is avoided. After the flow is made laminar completely,the pressure difference is obtained and it is thereby possible tomeasure the flowrate with high accuracy stably, even if the flowrate ofthe liquid is very small. Consequently, it is possible to supply theliquid of a small flowrate while controlling the flowrate with higheraccuracy in the liquid supply apparatus 1.

By using a long tube 143 as a pressure loss part to reduce the pressureof the liquid gradually in the flowmeter 14, even if the flowrate of theliquid which has a small flowrate is measured, a significant pressuredifference can be obtained without making the inner diameter of the tube143 extremely small. Therefore, it becomes possible to make the innerdiameter of the tube 143 relatively large and there is no need to makethe flow velocity of the liquid flowing through the tube 143 extremelyhigh. This results in preventing foreign substances from blocking thetube 143 and also occurring cavitation in the vicinity of an end of thetube 143 in the downstream side and the like. The flowmeter 14 isespecially suitable for the liquid supply apparatus 1 which needs highaccurate flowrate measurement of the liquid of the small flowrate.

FIG. 10 is a view illustrating a construction of a liquid supplyapparatus 1 a in accordance with the second preferred embodiment of thepresent invention. As shown in FIG. 10, the liquid supply apparatus 1 ahas the same constituents as the liquid supply apparatus 1 shown in FIG.1 and further comprises the other pump mechanism 13 a having the samestructure as the pump mechanism 13. In the following description, thepump mechanism 13 and the pump mechanism 13 a are respectively describedas “first pump mechanism 13” and “second pump mechanism 13 a” fordistinctiveness. Other constituent elements are the same as those ofFIG. 1 and the constituent elements are represented by the samereference signs in the following description. In FIG. 10, hatching ofcross sections are omitted.

In the liquid supply apparatus 1 a, the conduit 11 is divided into twoconduits between the liquid supply source 12, and the first pumpmechanism 13 and the second pump mechanism 13 a. Divided conduits 11connect between the first pump mechanism 13 and the second pumpmechanism 13 a, and the flowmeter 14. In two divided parts of theconduit 11, the first pump mechanism 13 is connected between the firstcheck valve 112 and the second check valve 113 which are installed onone divided conduit, and the second pump mechanism 13 a is connectedbetween the third check valve 112 a and the fourth check valve 113 awhich are installed on the other divided conduit. The flowmeter 14 formeasuring a flowrate of the liquid flowing through the conduit 11 islocated in a downstream side of a connected point of the above dividedconduits.

The second pump mechanism 13 a comprises, like the first pump mechanism13, the flexible chamber 131 a which is made of resin (hereinafter, theflexible chamber 131 a is referred to as “second flexible chamber 131a”. The flexible chamber 131 of the first pump mechanism 13 is referredto as “first flexible chamber 131” for distinctiveness), a pressurechamber 132 a housing the second flexible chamber 131 a, and anelectro-pneumatic regulator 133 a for adjusting a pressure in a spacebetween the pressure chamber 132 a and the second flexible chamber 131a.

The second flexible chamber 131 a comprises, like the first flexiblechamber 131, a bellows 1311 a, and a lower end of the bellows 1311 a ismade free. In the pressure chamber 132 a, like the pressure chamber 132shown in FIG. 2, provided are a displacement sensor for detecting adisplacement of the lower end of the bellows 1311 a with respect to thepressure chamber 132 a, and a leakage sensor for detecting a leakage, ifthere is a leakage of the liquid from the second flexible chamber 131 a.Also in the second pump mechanism 13 a, the displacement sensor detectswhether the second flexible chamber 131 a is in a compressed state, anexpanded state, or an intermediate state between the compressed stateand the expanded state.

The pressure chamber 132 a is connected to the electro-pneumaticregulator 133 a through a pneumatic valve 1331 a and is also connectedto the ejector 134 of the first pump mechanism 13 through a pneumaticvalve 1341 a. In other words, the first pump mechanism 13 and the secondpump mechanism 13 a share the ejector 134. The pneumatic valves 1331 a,1341 a are driven by electromagnetic valves 1332 a, 1342 a. In thesecond pump mechanism 13 a, these valves, the electro-pneumaticregulator 133 a, and the ejector 134 are controlled by the controller15, and the second flexible chamber 131 a is compressed and expanded. Bythis, the liquid is sucked from the liquid supply source 12 to be storedin the second flexible chamber 131 a, and it is pumped out to theconduit 11.

In the liquid supply apparatus 1 a, by control of the controller 15,compression of one chamber of the first flexible chamber 131 of thefirst pump mechanism 13 and the second flexible chamber 131 a of thesecond pump mechanism 13 a and concurrent expansion of the other chamberof the first flexible chamber 131 and the second flexible chamber 131 aare performed alternately to the first flexible chamber 131 and thesecond flexible chamber 131 a. By this, continuous supply of the liquidis performed.

FIG. 11 and FIG. 12 are views illustrating an operation flow of theliquid supply apparatus 1 a for supplying the liquid. FIG. 13 is a viewillustrating a state of switching between the first pump mechanism 13and the second pump mechanism 13 a in each step after the laterdiscussed Step S23. A reference sign of the step is assigned to aposition corresponding to each step. Next, referring to FIG. 11 to FIG.13, an operation flow of the liquid supply apparatus 1 a will bediscussed.

When the liquid is supplied by the liquid supply apparatus 1 a, like inthe first preferred embodiment, a user fills the first pump mechanism13, the second pump mechanism 13 a, and the conduit 11 with liquid forpreparation. The ejector 134 discharges air between the first flexiblechamber 131 and the pressure chamber 132, and pressure in the pressurechamber 132 is reduced. The first flexible chamber 131 changes from thecompressed state (see FIG. 3) to the expanded state (see FIG. 2), andthe liquid is sucked from the liquid supply source 12 to be stored inthe first flexible chamber 131. Concurrently with this operation, theejector 134 discharges air between the second flexible chamber 131 a andthe pressure chamber 132 a, and pressure in the pressure chamber 132 ais reduced. The second flexible chamber 131 a changes from thecompressed state to the expanded state, and the liquid is sucked fromthe liquid supply source 12 to be supplied to the second flexiblechamber 131 a and stored therein (Step S21).

After the first flexible chamber 131 and the second flexible chamber 131a becomes the expanded state, it is determined whether or not airremains in the first flexible chamber 131, the second flexible chamber131 a, and the conduit 11 (Step S22). In a case where air remains, theelectro-pneumatic regulators 133, 133 a supply air between the firstflexible chamber 131 and the pressure chamber 132, and between thesecond flexible chamber 131 a and the pressure chamber 132 a to increasepressures in the pressure chambers 132, 132 a. With this operation, thefirst flexible chamber 131 and the second flexible chamber 131 a changefrom the expanded state to the compressed state, and air in the firstflexible chamber 131, the second flexible chamber 131 a, and the conduit11 is discharged from a downstream side of the conduit 11 to the outsideof the liquid supply apparatus 1 a (Step S221).

After the first flexible chamber 131 and the second flexible chamber 131a are made to the compressed state, liquid supply to the firstflexible-chamber 131 and the second flexible chamber 131 a is restartedback to Step S21. In the liquid supply apparatus 1 a, liquid supply tothe first flexible chamber 131 and the second flexible chamber 131 a anddischarge of air from the first flexible chamber 131, the secondflexible chamber 131 a, and the conduit 11 are repeated (repeats StepsS21 to S221) until air in the first flexible chamber 131, the secondflexible chamber 131 a, and the conduit 11 is completely discharged andthe liquid filling is finished.

After air is completely discharged from the first flexible chamber 131,the second flexible chamber 131 a, and the conduit 11 (Step S22), theelectro-pneumatic regulator 133 of the first pump mechanism 13 suppliesair to the pressure chamber 132 to apply pressure to the first flexiblechamber 131, and the first flexible chamber 131 in the expanded state iscompressed. Pumping out of the liquid stored in the first flexiblechamber 131 to the conduit 11 is started, and the liquid is supplied tothe external apparatus or the like (Step S23).

In the second pump mechanism 13 a, a little before compression of thefirst flexible chamber 131 is stopped and pumping out of the liquid fromthe first pump mechanism 13 is stopped, air supply to the pressurechamber 132 a by the electro-pneumatic regulator 133 a is started, andthen compression of the second flexible chamber 131 a in the expandedstate is started. The liquid stored in the second flexible chamber 131 ais pumped out to the conduit 11 concurrently with pumping out of theliquid from the first flexible chamber 131 (Step S24).

Subsequently, compression of the first flexible chamber 131 is stoppedin the first pump mechanism 13 (Step S25). In the liquid supplyapparatus 1 a, also after compression of the first flexible chamber 131is stopped, compression of the second flexible chamber 131 a continuesin the second pump mechanism 13 a, and the liquid is continuously pumpedout to the conduit 11. In the first pump mechanism 13, once compressionof the first flexible chamber 131 is stopped, discharge of air from thepressure chamber 132 is started by the ejector 134 to expand the firstflexible chamber 131 in the compressed state. The liquid is sucked fromthe liquid supply source 12 to the first flexible chamber 131 to bestored therein (Step S26).

In the first pump mechanism 13, before compression of the secondflexible chamber 131 a (i.e., pumping out of the liquid from the secondpump mechanism 13 a) is stopped, discharge of air from the pressurechamber 132 by the ejector 134 (i.e., expansion of the first flexiblechamber 131) is stopped (Step S27). After that, a little beforecompression of the second flexible chamber 131 a is stopped, air supplyto the pressure chamber 132 by the electro-pneumatic regulator 133 isstarted to compress the first flexible chamber 131 in the expandedstate. Then the liquid stored in the first flexible chamber 131 ispumped out to the conduit 11 concurrently with pumping out of the liquidfrom the second flexible chamber 131 a (Step S31).

Subsequently, compression of the second flexible chamber 131 a isstopped in the second pump mechanism 13 a (Step S32). In the liquidsupply apparatus 1 a, also after compression of the second flexiblechamber 131 a is stopped, compression of the first flexible chamber 131continues in the first pump mechanism 13, and the liquid is continuouslypumped out to the conduit 11. In the second pump mechanism 13 a, oncecompression of the second flexible chamber 131 a is stopped, dischargeof air from the pressure chamber 132 a is started by the ejector 134,and the second flexible chamber 131 a in the compressed state isexpanded to increase a volume thereof. The liquid is sucked from theliquid supply source 12 to the second flexible chamber 131 a to bestored therein (Step S33).

In the second pump mechanism 13 a, before compression of the firstflexible chamber 131 (i.e., pumping out of the liquid from the firstpump mechanism 13) is stopped, discharge of air from the pressurechamber 132 a by the ejector 134 (i.e., expansion of the second flexiblechamber 131 a) is stopped (Step S34). Back to Step S24, a little beforecompression of the first flexible chamber 131 is stopped, air supply tothe pressure chamber 132 a by the electro-pneumatic regulator 133 a isstarted to apply pressure to the second flexible chamber 131 a in theexpanded state, and the second flexible chamber 131 a is compressed. Byreducing a volume of the second flexible chamber 131 a, the liquidstored in the second flexible chamber 131 a is pumped out to the conduit11 concurrently with pumping out of the liquid from the first flexiblechamber 131 (Step S24).

Subsequently, compression of the first flexible chamber 131 is complete(Step S25), and the first flexible chamber 131 is expanded to suck theliquid before stopping compression of the second flexible chamber 131 a(Steps S26, S27). After compression of the first flexible chamber 131and pumping out of the liquid are started, compression of the secondflexible chamber 131 a is stopped (Steps S31, S32). After that, beforestopping compression of the first flexible chamber 131, the secondflexible chamber 131 a is expanded to suck the liquid (Steps S33, S34),and back to Step S24 again.

As discussed above, in the liquid supply apparatus 1 a, Steps S24 to S34are repeated until it is determined liquid supply is complete. In otherwords, almost concurrent pumping out of the liquid from the secondflexible chamber 131 a to the conduit 11 and storing of the liquid inthe first flexible chamber 131, and almost concurrent pumping out of theliquid from the first flexible chamber 131 to the conduit 11 and storingof the liquid in the second flexible chamber 131 a, are alternatelyrepeated. As a result, pumping out of the liquid from the first pumpmechanism 13 and/or the second pump mechanism 13 a are continuouslyperformed in the liquid supply apparatus 1 a. In the liquid supplyapparatus 1 a, the second flexible chamber 131 a may be compressedbefore compression of the first flexible chamber 131. The initial liquidfilling may be performed by alternately repeating compression of onechamber of the first flexible chamber 131 and the second flexiblechamber 131 a and concurrent expansion of the other chamber.

In the liquid supply apparatus 1 a, while the first pump mechanism 13and the second pump mechanism 13 a are pumping out the liquid, that isto say, during Step S23 and repeated Step S24 to S34 shown in FIG. 11and FIG. 12, a flowrate control shown in FIG. 14 is continuouslyperformed. Next discussion will be made on an operation flow of theliquid supply apparatus 1 a for controlling a flowrate.

In the liquid supply apparatus 1 a, when the first pump mechanism 13starts pumping out of the liquid to the conduit 11 in Step S23 (see FIG.11, FIG. 13), like in the first preferred embodiment, a flowrate of theliquid flowing through the conduit 11 is measured by the flowmeter 14,and a measured flowrate is sent to the feedback controller 151 of thecontroller 15 (Step S41). Subsequently, it is determined whether or notthe measured flowrate obtained by the flowmeter 14 is equal to apredetermined flowrate (Step S42).

In a case where the measured flowrate differs from the predeterminedflowrate, the feedback controller 151 controls the electro-pneumaticregulator 133 of the first pump mechanism 13, and the pressure appliedto the first flexible chamber 131 is controlled so that the measuredflowrate is adjusted to the predetermined flowrate (Step S43). Also inthe second preferred embodiment, the feedback controller 151 utilizes aPID Control as a control method of the flowrate.

In the liquid supply apparatus 1 a, it is checked repeatedly whether ornot pumping out of the liquid from the first pump mechanism 13 and thesecond pump mechanism 13 a is complete (Step S44), in a case where it isnot complete, back to Step S41, the steps for measuring a flowrate tocontrol pressure(s) applied to the first flexible chamber 131 and/or thesecond flexible chamber 131 a (Steps S41 to S43) are repeated.

In the liquid supply apparatus 1 a, during Steps S23 to S24 and StepsS32 to S24 shown in FIG. 13, the first pump mechanism 13 is controlledand the measured flowrate is made equal to the predetermined flowrate.During Steps S25 to S31, a flowrate is measured by the flowmeter 14placed in a downstream side of the second pump mechanism 13 a, on thebasis of a measured flowrate, the electro-pneumatic regulator 133 a ofthe second pump mechanism 13 a is controlled. By this, the pressureapplied to the second flexible chamber 131 a is controlled so that themeasured flowrate is adjusted to the predetermined flowrate.

During Steps S24 to S25 and Steps S31 to S32, the electro-pneumaticregulators 133, 133 a of the first pump mechanism 13 and the second pumpmechanism 13 a are controlled on the basis of the measured flowrate ofthe flowmeter 14, so that pressures applied to the first flexiblechamber 131 and the second flexible chamber 131 a are parallelcontrolled. In other words, in the liquid supply apparatus 1 a, a periodafter starting pumping out of the liquid from the first flexible chamber131 and a period before ending pumping out of the liquid from the firstflexible chamber 131 respectively overlap a period before ending pumpingout of the liquid from the second flexible chamber 131 a and a periodafter starting pumping out of the liquid from the second flexiblechamber 131 a. In these overlapping periods, equivalent pressures areapplied to the first flexible chamber 131 and the second flexiblechamber 131 a to be controlled so that the measured flowrate of theflowmeter 14 is made equal to the predetermined flowrate.

FIG. 15 is a view illustrating a change of a flowrate of the liquidflowing through the conduit 11 in the liquid supply apparatus 1 a. Inthe liquid supply apparatus 1 a, in a case where compression of onechamber of the first flexible chamber 131 and the second flexiblechamber 131 a is started when compression of the other chamber continues(i.e., Steps S24, S31), pressure applied to the one chamber (i.e., acommand value of pressure sent to the electro-pneumatic regulator) ismade the same as pressure applied to the other chamber as discussedabove. At this time, since the flexible chamber started compression ismore expanded state than the flexible chamber under compression, areaction force by the bellows of the flexible chamber startedcompression is small. As a result, a flowrate of the liquid pumped outto the conduit 11 becomes slightly greater than the predeterminedflowrate during Steps S24 to S25 and Steps S31 to S32 as shown in FIG.15.

In the liquid supply apparatus 1 a, however, since a flowrate control isperformed on the basis of the measured flowrate of the flowmeter 14 asdiscussed above, such slight variations in flowrate are immediatelysuppressed. As a result, it is prevented great flowrate variationscausing problems occur in liquid supply, and it is possible to maintaina constant flowrate always in the liquid supply apparatus 1 a.

As discussed above, in the liquid supply apparatus 1 a, compression ofone chamber of the first flexible chamber 131 of the first pumpmechanism 13 and the second flexible chamber 131 a of the second pumpmechanism 13 a and concurrent expansion of the other chamber arealternately performed, the flowrate of the liquid flowing through theconduit 11 is measured by the flowmeter 14, and further on the basis ofthe measured flowrate, the pressures applied to the first flexiblechamber 131 and the second flexible chamber 131 a are controlled by thefeedback controller 151. In the liquid supply apparatus 1 a, it ispossible to supply the liquid of a small flowrate long hourscontinuously while controlling pressures applied to the first flexiblechamber 131 and the second flexible chamber 131 a with high accuracy tocontrol the flowrate accurately.

In the liquid supply apparatus 1 a, before compression of one chamber ofthe first flexible chamber 131 and the second flexible chamber 131 a isstopped, expansion of the other chamber is complete to startcompression. With this operation, by overlapping a starting period withan ending period of pumping movement of the liquid by the first pumpmechanism 13 and the second pump mechanism 13 a, it is possible tosuppress flowrate variations easily which occur in switching ofcompressions of the first flexible chamber 131 and the second flexiblechamber 131 a. As a result, it becomes possible to perform continuoussupply of the liquid of the small flowrate stably.

In the liquid supply apparatus 1 a, since the second pump mechanism 13 ahas the same constituents as the first pump mechanism 13 and the secondpump mechanism 13 a is made of resin with high durability againstvarious kinds of liquid, it is possible to supply various kinds ofliquid. Like the first flexible chamber 131, it is possible to change avolume of the second flexible chamber 131 a comprising the bellows 1311a easily, and it is also possible to suppress deterioration caused byrepeats of compression and expansion of the second flexible chamber 131a.

In the second pump mechanism 13 a, since the electro-pneumatic regulator133 a is used in compression of the second flexible chamber 13 la, it ispossible to control the pressure in the space between the pressurechamber 132 a and the second flexible chamber 131 a with high responseand high accuracy. By making the lower end of the second flexiblechamber 131 a free, it is possible to compress the second flexiblechamber 131 a stably and it is also possible to control a flowrate ofthe liquid to be supplied with higher accuracy. By positioning thedisplacement sensor and the leakage sensor in the pressure chamber 132a, it is possible to increase reliability of the liquid supply apparatus1.

In the liquid supply apparatus 1 a, like in the first preferredembodiment, it is possible to measure a flowrate with high accuracystably by the flowmeter 14, even if the flowrate of the liquid is verysmall.

Next, discussion will be made on a liquid supply apparatus in accordancewith the third preferred embodiment of the present invention. The liquidsupply apparatus in accordance with the third preferred embodiment isprovided a pump mechanism 13 b shown in FIG. 16 instead of the pumpmechanism 13 of the liquid supply apparatus 1 shown in FIG. 1. Otherconstituent elements are the same as those of FIG. 1 and the constituentelements are represented by the same reference signs in the followingdescription.

In the pump mechanism 13b of the liquid supply apparatus in accordancewith the third preferred embodiment, compression and expansion of aflexible chamber 131 b is performed by a motor which is a differentpower source from that of the pump mechanism 13 of the liquid supplyapparatus 1 shown in FIG. 1. As shown in FIG. 16, in the pump mechanism13 b, a moving mechanism 137 for compressing or expanding the flexiblechamber 131 b by moving a lower end of the flexible chamber 131 b in avertical direction and a motor 138 for driving the moving mechanism 137are provided, instead of the pressure chamber 132 of the pump mechanism13, the electro-pneumatic regulator 133, the ejector 134, and variouspneumatic valves and electromagnetic valves shown in FIG. 1.

The moving mechanism 137 comprises a moving plate 1371 connected to thelower end of the flexible chamber 131 b, a ball screw 1372 extending inthe vertical direction, a nut 1373 which is fixed on the moving plate1371 and into which the ball screw 1372 is inserted, a guide 1374 forleading the moving plate 1371 in the vertical direction, and a timingbelt 1375 for connecting the ball screw 1372 to the motor 138. An outputtorque of the motor 138 is controllable and to the motor 138 a torquecontrol amplifier 1381 is connected.

In the moving mechanism 137, the motor 138 rotates the ball screw 1372,so that the moving plate 1371 moves along the guide 1374 in the verticaldirection smoothly. When the moving plate 1371 moves upward to be drivenby the motor 138, the lower end of the flexible chamber 131 b also movesupward (i.e., toward an upper end of the flexible chamber 131 b) toapply pressure to the flexible chamber 131 b, and then the liquid in theflexible chamber 131 b is pumped out to the conduit 11. In other words,the moving mechanism 137 functions as a pressure mechanism for applyingpressure to the flexible chamber 131 b by a torque outputted from themotor 138.

When the moving plate 1371 moves downward to be driven by the motor 138,the lower end of the flexible chamber 131 b moves away from the upperend to reduce pressure in the flexible chamber 131 b. By this, theliquid is sucked from the liquid supply source 12 (see FIG. 1) to besupplied to the flexible chamber 131 b and stored therein.

In the liquid supply apparatus in accordance with the third preferredembodiment, by compressing the flexible chamber 131 b in the pumpmechanism 13 b, the liquid in the flexible chamber 131 b is pumped outto the conduit 11. While the liquid is flowing through the conduit 11, aflowrate of the liquid flowing through the conduit 11 is measured by theflowmeter 14 (see FIG. 1) placed in a downstream side of the pumpmechanism 13 b. On the basis of a measured flowrate, the output torqueof the motor 138 is controlled by the feedback controller 151 (seeFIG. 1) of the controller 15 through the torque control amplifier 1381,and the pressure applied to the flexible chamber 131 b is controlled sothat the measured flowrate is adjusted to a predetermined flowrate.

As discussed above, in the liquid supply apparatus in accordance withthe third preferred embodiment, since the pump mechanism 13 b can bedriven without a compressor or a vacuum source, it is possible tosimplify the construction of the liquid supply apparatus.

Next, referring to FIG. 17, a substrate processing apparatus 2comprising the liquid supply apparatus 1 shown in FIG. 1 in accordancewith the fourth preferred embodiment of the present invention will bediscussed. The substrate processing apparatus 2 is a so-called singlewafer-type processing apparatus for etching one semiconductor substrate9 (hereinafter, referred to as simply “substrate 9”).

As shown in FIG. 17, the substrate processing apparatus 2 includes afirst conduit 21 through which pure water flows and a second conduit 22through which hydrofluoric acid flows. The first conduit 21 and thesecond conduit 22 are connected at a downstream of both conduits. At aconnected point of the first conduit 21 and the second conduit 22 amixing valve 241 is installed, the pure water from the first conduit 21and the hydrofluoric acid from the second conduit 22 are mixed in themixing valve 241 and a processing liquid is generated.

The first conduit 21 is connected to an external pure water supplyapparatus through a valve 211 and a regulator 212 in an upstream side ofthe first conduit 21. In an upstream side of the second conduit 22, theliquid supply apparatus 1 for supplying the hydrofluoric acid inaccordance with the first preferred embodiment is placed. In the flowingdescription, the constituent elements of the liquid supply apparatus 1will be discussed referring to the reference signs in FIG. 1.

In the substrate processing apparatus 2, a third conduit 24 throughwhich the processing liquid which is a mixture of the pure water and thehydrofluoric acid flows is provided in a downstream side of the mixingvalve 241, and in a downstream side of the third conduit 24 (i.e., adownstream side of the connected point of the first conduit 21 and thesecond conduit 22) a substrate holding part 26 for holding the substrate9 is positioned. A nozzle 27 is located in an upper part of thesubstrate holding part 26, and the nozzle 27 serves as a processingliquid supply part which is connected to the downstream side of thethird conduit 24 and supplies the processing liquid to the substrate 9.

The substrate holding part 26 has a chuck 261 for holding theapproximately disk-shaped substrate 9 on the lower surface and theperiphery of the substrate 9, a rotating mechanism 262 for rotating thesubstrate 9, and a process cup 263 for covering the circumference of thechuck 261. The rotating mechanism 262 has a shaft 2621 coupled to thebottom of the chuck 261 and a motor 2622 for rotating the shaft 2621. Bydriving the motor 2622, the substrate 9 rotates together with the shaft2621 and the chuck 261. The process cup 263 has a side wall 2631, placedin the circumference of the chuck 261, for preventing the processingliquid supplied to the substrate 9 from splashing around, and an outlet2632, provided in the bottom of the process cup 263, for discharging theprocessing liquid supplied to the substrate 9.

In the substrate processing apparatus 2, by opening the valve 211, thepure water is supplied from the pure water supply apparatus to the firstconduit 21. At the same time, by driving the pump mechanism 13 (seeFIG. 1) of the liquid supply apparatus 1 to apply pressure to theflexible chamber 131 where the hydrofluoric acid is stored in advance,the hydrofluoric acid is pumped out from the flexible chamber 131 to theconduit 11 and is supplied to the second conduit 22. In the mixing valve241, the hydrofluoric acid supplied to the second conduit 22 is mixedwith the pure water supplied to the first conduit 21 and the processingliquid of a dilute hydrofluoric acid is generated.

The processing liquid generated in the mixing valve 241 is supplied tothe nozzle 27 through the third conduit 24 and is ejected from thenozzle 27 toward the center of the substrate 9 only a required amount.The substrate 9 is hold by the substrate holding part 26 and is rotated.The processing liquid supplied from the nozzle 27 spreads in all areasof the top of the substrate 9 while moving a top of the substrate 9toward the outside thereof by the centripetal force, and then etching ofthe substrate 9 is performed. When the processing liquid moves out ofthe edge of the substrate 9, it is away from the substrate 9 and isreceived by the side wall 2631 of the process cup 263 or falls on thebottom of the process cup 263 directly and then the processing liquid isdischarged from the outlet 2632.

In the liquid supply apparatus 1 of the substrate processing apparatus2, the flowrate of the hydrofluoric acid flowing at a small flowrate ismeasured by the flowmeter 14 (see FIG. 1) with high accuracy stably, thepressure applied to the flexible chamber 131 of the pump mechanism 13 iscontrolled by the controller 15 (see FIG. 1) on the basis of a measuredflowrate and a flowrate predetermined in advance, and thus it becomespossible to supply the hydrofluoric acid to the second conduit 22 whileperforming the flowrate control of the hydrofluoric acid of the smallflowrate accurately. With this operation, in the substrate processingapparatus 2, a small supply rate of the hydrofluoric acid to the mixingvalve 241 is controlled with high accuracy, and the processing liquidwhere the hydrofluoric acid is mixed at the desired concentrationaccurately is generated. Consequently, in the substrate processingapparatus 2, it is possible to perform etching of the substrate 9 withthe processing liquid where the hydrofluoric acid is mixed at thedesired concentration accurately. By performing etching with the dilutehydrofluoric acid of a concentration controlled with high accuracy, theetching rate is controlled high accurately and a more preferableprocessing result can be obtained. Also, by lowering the etching rate tosuppress processing time variation in the center and the edge of thesubstrate 9, it is possible to improve uniformity of etching quality ina whole upper surface of the substrate 9.

Next, referring to FIG. 18, a substrate processing apparatus 2 acomprising the liquid supply apparatus 1 a shown in FIG. 10 inaccordance with the fifth preferred embodiment of the present inventionwill be discussed. The substrate processing apparatus 2 a is a so-calledbatch-type processing apparatus for etching a plurality of substrates 9simultaneously. As shown in FIG. 18, in the substrate processingapparatus 2 a, the liquid supply apparatus 1 a shown in FIG. 10 isplaced instead of the liquid supply apparatus 1 of the substrateprocessing apparatus 2 shown in FIG. 17, and instead of the substrateholding part 26 and the nozzle 27, a process bath 25 is located in thedownstream side of the third conduit 24 (i.e., the downstream side ofthe connected point of the first conduit 21 and the second conduit 22).The process bath 25 stores the processing liquid and where theapproximately disk-shaped substrates 9 are dipped vertically. Otherconstituent elements are the same as those of FIG. 17 and theconstituent elements are represented by the same reference signs in thefollowing description. The constituent elements of the liquid supplyapparatus 1 a will be discussed referring to the reference signs in FIG.10.

As shown in FIG. 18, the substrate processing apparatus 2 a, like in thefourth preferred embodiment, includes the first conduit 21 through whichthe pure water flows, the second conduit 22 through which thehydrofluoric acid flows and connected to the first conduit 21 in themixing valve 241, the liquid supply apparatus 1 a in accordance with thesecond preferred embodiment, placed in the upstream side of the secondconduit 22 to supply the hydrofluoric acid to the second conduit 22, andthe third conduit 24 installed in the downstream side of the mixingvalve 241 and through which the processing liquid, which is the mixtureof the pure water and the hydrofluoric acid, flows.

In the substrate processing apparatus 2 a, like in the fourth preferredembodiment, the pure water supplied to the first conduit 21 and thehydrofluoric acid supplied to the second conduit 22 are mixed in themixing valve 241 and the processing liquid of the dilute hydrofluoricacid solution is generated. At this time, in the liquid supply apparatus1 a, the flowrate of the hydrofluoric acid flowing at the very smallflowrate is stably measured by the flowmeter 14 (see FIG. 10) with highaccuracy, pressures applied to the first flexible chamber 131 and thesecond flexible chamber 131 a (see FIG. 10) are controlled by thecontroller 15 (see FIG. 10) on the basis of the measured flowrate andthe predetermined flowrate, and thus the hydrofluoric acid is suppliedto the mixing valve 241 through the second conduit 22 while performingthe flowrate control of the hydrofluoric acid of the small flowrateaccurately. As a result, the processing liquid where the hydrofluoricacid is mixed accurately at the desired concentration is generated.

The processing liquid generated in the mixing valve 241 is supplied tothe process bath 25 from the bottom thereof through the third conduit24. In the process bath 25, the plurality of substrates 9 held in theprocess bath 25 are dipped gradually from the bottoms into theprocessing liquid which is supplied to the process bath 25 and is storedtherein, and then etching of the substrates 9 is performed.

In the substrate processing apparatus 2 a, like in the fourth preferredembodiment, it is possible to perform etching of the substrate 9 withthe processing liquid where the hydrofluoric acid is mixed accurately atthe desired concentration. By performing etching with the dilutehydrofluoric acid of a concentration controlled with high accuracy, theetching rate is controlled high accurately and it is possible to obtaina more preferable processing result. Also, by lowering the etching rateto suppress processing time variation in an upper side and a lower sideof the substrate 9, it is possible to improve uniformity of etchingquality in a whole upper surface of the substrate 9.

Since in the substrate processing apparatus 2 a it is possible to supplythe hydrofluoric acid of a small flowrate long hours continuously whilecontrolling the flowrate accurately by the liquid supply apparatus 1 a,the substrate processing apparatus 2 a is especially suitable forbatch-type etching (and the other substrate processing) which requires alarge amount of processing liquid in one process. In the liquid supplyapparatus 1 a, by overlapping a starting period with an ending period ofpumping movement of the liquid by the first pump mechanism 13 and thesecond pump mechanism 13 a, it is possible to suppress flowratevariations easily which occur in switching of compressions of the firstflexible chamber 131 and the second flexible chamber 131 a, and thus itbecomes possible to keep the processing liquid for etching of thesubstrates 9 at the desired concentration easily.

Though the preferred embodiments of the present invention have beendiscussed above, the present invention is not limited to theabove-discussed preferred embodiments, but allows various variations.

The flexible chambers provided in respective pump mechanisms of theliquid supply apparatuses in accordance with the above preferredembodiments may be made of various materials except resin. Each flexiblechamber does not necessarily comprise the bellows and for example, thewhole of the flexible chamber may be almost spherical. Also in thiscase, in the liquid supply apparatuses in accordance with the first andsecond preferred embodiments, an almost spherical flexible chamberapplied pressure in the pressure chamber is compressed, and the liquidis pumped out to the conduit 11.

In the liquid supply apparatuses in accordance with the first and secondpreferred embodiments, in sucking the liquid from the liquid supplysource 12 by expanding the flexible chamber, pressure reduction is notnecessarily performed until pressure in the pressure chamber becomesnegative. For example, the bellows expands by a reaction force of thebellows compressed by reducing pressure around the flexible chamber to acertain degree, and the liquid may be sucked from the liquid supplysource 12. After sealing the liquid supply source 12, a pump mechanismis provided, by applying pressure to the liquid in the liquid supplysource 12 to pump out the liquid to the pump mechanism, the liquid maybe supplied to the flexible chamber.

In the liquid supply apparatus 1 a in accordance with the secondpreferred embodiment, two pump mechanisms 13 b of the liquid supplyapparatus in accordance with the third preferred embodiment may beprovided instead of the first pump mechanism 13 and the second pumpmechanism 13 a.

The displacement sensor 135 and the leakage sensor 136 positioned in thepump mechanism 13 are not limited to the structures described in theabove preferred embodiments and they may have various structures. Forexample, a float type leakage sensor 136 may be used. In a case whereelectricity is not available in a liquid detection because of lowconductivity of a liquid in the flexible chamber or the like, theleakage sensor 136 may have a structure where the leakage sensor 136receives a reflection light of a light emitted toward the bottom of thepressure chamber and detects a leakage according to a change of opticalproperties of the reflection light.

The tube 143 of the flowmeter 14 is not necessarily made of resin and itmay be made of other materials. In this case, it is preferable that thetube 143 is made of materials with high durability against various kindsof liquid. The storage part 145 and the operation part 146 of theflowmeter 14 may be formed integrally with the feedback controller 151of the controller 15.

In the substrate processing apparatus 2 in accordance with the fourthpreferred embodiment, the liquid supply apparatus 1 a having the twoflexible chambers or the liquid supply apparatus in accordance with thethird preferred embodiment where the motor 138 is the power source maybe placed instead of the liquid supply apparatus 1 having one flexiblechamber 131. In the substrate processing apparatus 2 a in accordancewith the fifth preferred embodiment, the liquid supply apparatus 1 orthe liquid supply apparatus in accordance with the third preferredembodiment may be placed instead of the liquid supply apparatus 1 a.

In the substrate processing apparatuses in accordance with the fourthand fifth preferred embodiments, liquids except the pure water and thehydrofluoric acid may be mixed, and other processes (cleaning process,for example) except etching of the substrate 9 may be performed.

While the invention has been shown and described in detail, theforegoing description is in all aspects illustrative and notrestrictive. It is therefore understood that numerous modifications andvariations can be devised without departing from the scope of theinvention.

This application claims priority benefit under 35 U.S.C. Section 119 ofJapanese Patent Application No. 2004-375294 filed in the Japan PatentOffice on Dec. 27, 2004, the entire disclosure of which is incorporatedherein by reference.

1. A liquid supply apparatus for supplying a liquid, comprising: a pumpmechanism for pumping out a liquid to a conduit by applying pressure toa flexible chamber to reduce a volume of said flexible chamber; aflowmeter placed in a downstream side of said pump mechanism formeasuring a flowrate of said liquid flowing through said conduit; and acontroller for sending an electrical signal to said pump mechanism, saidelectrical signal controlling pressure applied to said flexible chamberso that said flowrate of said liquid flowing through said conduit isadjusted to a predetermined flowrate on the basis of a flowrate of saidliquid obtained by said flowmeter.
 2. The liquid supply apparatusaccording to claim 1, wherein said flexible chamber is made of resin. 3.The liquid supply apparatus according to claim 1, wherein said flexiblechamber comprises a bellows.
 4. The liquid supply apparatus according toclaim 1, wherein said pump mechanism comprises a pressure chamberhousing said flexible chamber; and an electro-pneumatic regulator foradjusting pressure in a space between said pressure chamber and saidflexible chamber.
 5. The liquid supply apparatus according to claim 1,wherein said flexible chamber comprises a bellows, and said pumpmechanism comprises a pressure chamber housing said flexible chamber;and an electro-pneumatic regulator for adjusting pressure in a spacebetween said pressure chamber and said flexible chamber, wherein one endof said flexible chamber is fixed to said pressure chamber and the otherend is made free.
 6. The liquid supply apparatus according to claim 5,wherein said pump mechanism further comprises a displacement sensor fordetecting a displacement of said other end with respect to said pressurechamber.
 7. The liquid supply apparatus according to claim 4, whereinsaid pump mechanism further comprises a leakage sensor located on aninner side of a bottom of said pressure chamber for detecting a leakageof said liquid from said flexible chamber.
 8. The liquid supplyapparatus according to claim 1, wherein said pump mechanism comprises amotor where an output torque is controlled; and a press mechanism forapplying pressure to said flexible chamber by a torque outputted fromsaid motor.
 9. The liquid supply apparatus according to claim 1, furthercomprising: another pump mechanism which has the same structure as saidpump mechanism, wherein compression of one chamber of said flexiblechamber of said pump mechanism and another flexible chamber of saidanother pump mechanism and concurrent expansion of the other chamber ofsaid flexible chamber and said another flexible chamber are performedalternately to said flexible chamber and said another flexible chamberby control of said controller.
 10. The liquid supply apparatus accordingto claim 9, wherein before compression of said one chamber is stopped,expansion of said other chamber is stopped and compression of said otherchamber is started.
 11. The liquid supply apparatus according to claim1, wherein said flowmeter is a differential pressure flowmeter, and saiddifferential pressure flowmeter comprises a round tube provided as apart of said conduit in which a flow of said liquid with a Reynoldsnumber less than or equal to 2000 is formed; a first pressure sensorplaced between said pump mechanism and said round tube for measuring apressure of said liquid flowing into said round tube; and a secondpressure sensor placed in a downstream side of said round tube formeasuring a pressure of said liquid flowing out of said round tube. 12.The liquid supply apparatus according to claim 11, wherein said roundtube is made of resin.
 13. A substrate processing apparatus forprocessing a substrate, comprising: a first conduit through which afirst liquid flows; a second conduit through which a second liquidflows, said second conduit connected to said first conduit; a liquidsupply apparatus installed on an upstream side of said second conduitfor supplying said second liquid; and a process bath, located in adownstream side of a connected point of said first conduit and saidsecond conduit, for storing a processing liquid which is a mixture ofsaid first liquid and said second liquid, in which a substrate beingdipped, wherein said liquid supply apparatus comprises a pump mechanismfor pumping out said second liquid to a conduit connected to said secondconduit by applying pressure to a flexible chamber to reduce a volume ofsaid flexible chamber; a flowmeter placed in a downstream side of saidpump mechanism for measuring a flowrate of said second liquid flowingthrough said conduit; and a controller for sending an electrical signalto said pump mechanism, said electrical signal controlling pressureapplied to said flexible chamber so that said flowrate of said secondliquid flowing through said conduit is adjusted to a predeterminedflowrate on the basis of a flowrate of said second liquid obtained bysaid flowmeter.
 14. The substrate processing apparatus according toclaim 13, wherein said flexible chamber is made of resin.
 15. Thesubstrate processing apparatus according to claim 13, wherein saidflexible chamber comprises a bellows.
 16. The substrate processingapparatus according to claim 13, wherein said pump mechanism comprises apressure chamber housing said flexible chamber; and an electro-pneumaticregulator for adjusting pressure in a space between said pressurechamber and said flexible chamber.
 17. The substrate processingapparatus according to claim 13, wherein said liquid supply apparatusfurther comprises another pump mechanism which has the same structure assaid pump mechanism, and compression of one chamber of said flexiblechamber of said pump mechanism and another flexible chamber of saidanother pump mechanism and concurrent expansion of the other chamber ofsaid flexible chamber and said another flexible chamber are performedalternately to said flexible chamber and said another flexible chamberby control of said controller.
 18. The substrate processing apparatusaccording to claim 17, wherein before compression of said one chamber isstopped, expansion of said other chamber is stopped and compression ofsaid other chamber is started.
 19. The substrate processing apparatusaccording to claim 13, wherein said flowmeter is a differential pressureflowmeter, and said differential pressure flowmeter comprises a roundtube provided as a part of said conduit in which a flow of said secondliquid with a Reynolds number less than or equal to 2000 is formed; afirst pressure sensor placed between said pump mechanism and said roundtube for measuring a pressure of said second liquid flowing into saidround tube; and a second pressure sensor placed in a downstream side ofsaid round tube for measuring a pressure of said second liquid flowingout of said round tube.
 20. A substrate processing apparatus forprocessing a substrate, comprising: a substrate holding part for holdinga substrate; a first conduit through which a first liquid flows; asecond conduit through which a second liquid flows, said second conduitconnected to said first conduit; a liquid supply apparatus installed onan upstream side of said second conduit for supplying said secondliquid; and a processing liquid supply part, located in a downstreamside of a connected point of said first conduit and said second conduit,for supplying a processing liquid which is a mixture of said firstliquid and said second liquid to said substrate, wherein said liquidsupply apparatus comprises a pump mechanism for pumping out said secondliquid to a conduit connected to said second conduit by applyingpressure to a flexible chamber to reduce a volume of said flexiblechamber; a flowmeter placed in a downstream side of said pump mechanismfor measuring a flowrate of said second liquid flowing through saidconduit; and a controller for sending an electrical signal to said pumpmechanism, said electrical signal controlling pressure applied to saidflexible chamber so that said flowrate of said second liquid flowingthrough said conduit is adjusted to a predetermined flowrate on thebasis of a flowrate of said second liquid obtained by said flowmeter.21. The substrate processing apparatus according to claim 20, whereinsaid flexible chamber is made of resin.
 22. The substrate processingapparatus according to claim 20, wherein said flexible chamber comprisesa bellows.
 23. The substrate processing apparatus according to claim 20,wherein said pump mechanism comprises a pressure chamber housing saidflexible chamber; and an electro-pneumatic regulator for adjustingpressure in a space between said pressure chamber and said flexiblechamber.
 24. The substrate processing apparatus according to claim 20,wherein said liquid supply apparatus further comprises another pumpmechanism which has the same structure as said pump mechanism, andcompression of one chamber of said flexible chamber of said pumpmechanism and another flexible chamber of said another pump mechanismand concurrent expansion of the other chamber of said flexible chamberand said another flexible chamber are performed alternately to saidflexible chamber and said another flexible chamber by control of saidcontroller.
 25. The substrate processing apparatus according to claim24, wherein before compression of said one chamber is stopped, expansionof said other chamber is stopped and compression of said other chamberis started.
 26. The substrate processing apparatus according to claim20, wherein said flowmeter is a differential pressure flowmeter, andsaid differential pressure flowmeter comprises a round tube provided asa part of said conduit in which a flow of said second liquid with aReynolds number less than or equal to 2000 is formed; a first pressuresensor placed between said pump mechanism and said round tube formeasuring a pressure of said second liquid flowing into said round tube;and a second pressure sensor placed in a downstream side of said roundtube for measuring a pressure of said second liquid flowing out of saidround tube.
 27. A liquid supply method for supplying a liquid,comprising the steps of: a) storing a liquid supplied from a liquidsupply source in a flexible chamber by expanding said flexible chamberto increase a volume of said flexible chamber in a pump mechanism; andb) pumping out said liquid to a conduit by applying pressure to saidflexible chamber to reduce said volume of said flexible chamber, whereinsaid step b) comprises b1) measuring a flowrate of said liquid flowingthrough said conduit in a downstream side of said pump mechanism; andb2) controlling pressure applied to said flexible chamber so that saidflowrate of said liquid flowing through said conduit is adjusted to apredetermined flowrate on the basis of said flowrate measured in saidstep b1).
 28. The liquid supply method according to claim 27, furthercomprising the steps of: c) storing said liquid supplied from saidliquid supply source in another flexible chamber by expanding saidanother flexible chamber to increase a volume of said another flexiblechamber in another pump mechanism; and d) pumping out said liquid tosaid conduit by applying pressure to said another flexible chamber toreduce said volume of said another flexible chamber, wherein said stepd) comprises d1) measuring a flowrate of said liquid flowing throughsaid conduit in a downstream side of said another pump mechanism; andd2) controlling pressure applied to said another flexible chamber sothat said flowrate of said liquid flowing through said conduit isadjusted to said predetermined flowrate on the basis of said flowratemeasured in said step d1), wherein said step a) and said step d) areperformed almost concurrently, said step b) and said step c) areperformed almost concurrently, and said step a) and said step d), andsaid step b) and said step c) are performed alternately.
 29. The liquidsupply method according to claim 28, wherein said step b) starts beforesaid step d) ends, and said step d) starts before said step b) ends.